[unic-archon-dlc] QA workflow: add verify-pr-base guard after merge-pr

[orioltf]

Parent

docs/issues/unic-archon-dlc/PRD.md

What to build

qa.yaml currently calls merge-pr (which runs the configured tracker's merge CLI command) but does not verify the PR targets the correct base branch first. If the PR was opened against the wrong target — e.g. main instead of develop on a Gitflow project — the merge silently ships to the wrong branch.

Add a verify-pr-base bash node that runs before merge-pr:

1. Reads the configured branching strategy from .archon/unic-dlc.config.json.
2. Derives the expected base branch (develop for Gitflow, main for GitHub Flow).
3. For GitHub tracker: calls gh pr view --json baseRefName and compares.
4. For ADO tracker: calls az repos pr show and compares targetRefName.
5. For Jira / local: logs a warning and continues (no CLI to query PR base).
6. If the base is wrong: logs a clear error with the expected vs actual branch names and exits non-zero, preventing merge-pr from running.

This is a YAML-only addition of one bash node with an inline shell snippet — no lib modules or tests are added.

Acceptance criteria

• qa.yaml has a verify-pr-base bash node with depends_on: [uat-gate].
• merge-pr has depends_on: [verify-pr-base].
• For GitHub and ADO trackers, the node exits non-zero with a clear message if the PR base does not match the expected branch.
• For Jira and local trackers, the node logs a warning and exits zero (no-op).
• pnpm check passes at repo root after the change.

Blocked by

None — can start immediately.

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PRD: docs/issues/unic-archon-dlc/PRD.md
Migrated from: docs/issues/unic-archon-dlc/16-qa-verify-pr-base.md (source removed after migration)
Touched by PRs: #39